JP3246526B2 - Thermal recording material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive recording material,
In particular, the present invention relates to a heat-sensitive recording material having significantly improved image stability.

[0002]

2. Description of the Related Art In general, a thermosensitive recording material mainly comprises a color developing system comprising a colorless or pale-color coloring dye as a coloring agent on a support such as paper, synthetic paper, plastic film and the like, and a developing agent which causes the coloring to occur when heated. A thermosensitive coloring layer as a component is provided, and a colored image can be obtained by heating with a hot pen, a thermal head, a laser beam, a strobe lamp or the like. Compared to other recording materials, this recording material can be recorded in a short time with a relatively simple device without performing complicated processing such as development and fixing, has low noise generation and environmental pollution, and has a low cost. It is used for copying books, documents, etc. due to its low cost and other advantages, as well as electronic calculators, facsimile machines, ticket vending machines,
It is useful as various recording materials such as labels and recorders.

As a color-forming dye used for a heat-sensitive recording material, for example, a colorless or light-colored leuco dye having a lactone, lactam or spiropyran ring has been used, and a phenolic compound has been conventionally used as a developer. .
Recording materials using this color former and developer are widely used because of their high image density and high whiteness of the background. However, an image formed by such a leuco dye and a phenolic developer has a poor storage stability because the color forming system is a reversible process, and if the printed image is left as it is for a long time, the image will not be formed. It has the major disadvantage that the image is easily discolored by fading or by contact with water, oil, plasticizer, or the like.

[0004] In order to enhance the preservability of such leuco dye-based color images, various studies have been made on developers. For example, Japanese Patent Application Laid-Open No. 57-199686 proposes to improve the plasticizer resistance by using a benzophenone derivative having a sulfonyl group. However, such a sulfonic acid type developer is used in a non-image area. It is hard to say that it is practically poor in storage stability.

JP-A-59-185693 proposes to use a metal salt of an aromatic carboxylic acid and an aliphatic carboxylic acid to improve the storability of an image and the plasticizer resistance. The strength of the image to the plasticizer and the color development thereof are not sufficient, and are not practical.

JP-A-63-45087 discloses a sulfonium salt compound, and JP-A-1-2940088 discloses a sulfonium salt compound having a benzyl group as one of the substituents and an aromatic ammonium salt. The use of a color developer has been proposed to improve the image stability with respect to a plasticizer and to prevent the non-image portion from being colored by an organic solvent. It is considered that a developer of this type generates a cation species such as a benzyl cation by thermal decomposition upon heating, and causes the electron-donating leuco dye to develop color. However, since such a thermal decomposition process requires a considerable amount of heat energy, it is difficult to say that a heat source used for ordinary thermal recording has a poor coloring property and is not practical.

In Japanese Patent Application Laid-Open Nos. 59-109388 and 1-178489, it has been proposed to use a sulfonic acid ester derivative as a color developer, but its color developability and image strength are insufficient. It is hard to say that it is practical.

Further, JP-A-2-120086 discloses that a colorant is formed by forming a hydrogen-bonded molecular complex between bisphenol A and another phenolic compound or an amine compound to use a plasticizer and a plasticizer. It has been proposed to improve the performance, but in such a system,
Since a phenolic compound such as bisphenol A acts as a color developer, the plasticizer resistance of the image is not fundamentally improved, and is not practical at present.

Japanese Patent Application Laid-Open No. Sho 62-267186 discloses that
The color development sensitivity is improved by using an aromatic phosphate and an aromatic phosphite as a sensitizer, and JP-A-3-138195 discloses that a phosphate having a phenolic hydroxyl group is used as a developer. Although it has been proposed to improve the image stability by doing so, it is difficult to say that the image strength is sufficient, and it is not practical.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat-sensitive recording material which is excellent in color development and image reliability.

[0011]

According to Means for Solving the Problems] The present invention, in supporting lifting member, and leuco dyes coloring by opening the lactone ring has a lactone ring, irreversible lactone ring of the leuco dye A heat-sensitive recording material is provided, comprising a heat-sensitive coloring layer having a color-developing compound represented by the following general formula ( I ) acting on a ring-opening reaction as a main component:

Embedded image(Where R₁Is an alkyl group having 1 to 6 carbon atoms,
Alkyl group, R_Two~ R₆Is hydrogen, halogen, hydroxyl, nitro
B, amino, alkyl, alkenyl, aralkyl
And aryl groups, and these groups are
Or these groups form a ring with each other
It may be. Y is -SO_ThreeGroup-containing anion
tableI forgot. ) Also Plastic sphere between the support and the thermosensitive coloring layer
Characterized in that an intermediate layer mainly composed of hollow particles is provided.
The heat-sensitive recording material is provided.

The coloring system in the thermosensitive coloring layer of this type of thermosensitive recording material is as follows. A colorless leuco dye having a lactone ring in the molecule and developing a color by a cleavage reaction of the lactone ring is contacted with a developer contained in the thermosensitive coloring layer at the time of heating to give a reaction formula shown in the following Table 1. The lactone ring is cleaved and the color develops. But,
Since this color development reaction is a reversible reaction, the reverse reaction (lactone ring opening) easily proceeds, and the formed image disappears.

[Table 1]

[0013] where, as shown in the following reaction formula in Table 2, for example, the general formula R-X (X represents halogen) simultaneously esterified When the ring-opening the lactone ring by color-developing compound represented by By including a compound that allows the reaction to proceed, the esterification reaction proceeds at the same time as the leuco dye develops color, making it possible to make the color development process irreversible.

[Table 2]

FIG. 1 and FIG.
(N, N-diethylamino) -6-methyl-7-anilinofluoran and methyl iodide (see
2 shows an infrared spectral absorption spectrum chart and a magnetic resonance spectrum chart of a black color body obtained by heating and coloring using the compound of the invention) . These spectra, the black coloring material can be seen to have ₃ groups -COOCH.

In the present invention, the compound represented by the general formula (I) can be used as the color-developing compound in the same manner as in the methyl iodide . Further, the amount of the color developing compound used in the present invention is based on 1 part by weight of the leuco dye.
0.1 to 10 parts by weight .

Hereinafter, the color developing compound used in the present invention.
The present invention is not limited to these.
is not. The compounds represented by the general formula ( I ) are shown in Table 3 below.

[Table 3- (1)]

[0017]

[Table 3- (2)]

[0018]

[Table 3- (3)]

[0019]

[Table 3- (4)]

[0020]

[Table 3- (5)]

[0021]

[Table 3- (6)]

[0022]

[Table 3- (7)]

[0023]

[Table 3- (8)]

[0024]

[Table 3- (9)]

In the present invention, an intermediate layer containing plastic spherical hollow particles as a main component may be provided between the support and the thermosensitive coloring layer. Since the intermediate layer contains hollow particles as a main component, it acts as a heat insulating layer, and a heat-sensitive recording material capable of forming a high-density image even with low energy can be obtained by efficiently utilizing heat energy from a thermal head or the like. The spherical hollow particle used in the present invention is a fine hollow particle which has a thermoplastic resin as a shell and contains air and other gas inside, and is in a foamed state.

In the present invention, an inorganic or / and organic pigment may be optionally added to the intermediate layer. In this case, a pigment having an oil absorption of 30 ml / 100 g or more, preferably 80 ml / 100 g or more is used. Is selected. As these inorganic and / or organic pigments, one or more of pigments commonly used in this type of heat-sensitive recording material can be selected. Specific examples thereof include calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, talc,
In addition to surface-treated inorganic pigments such as calcium and silica,
Organic pigments such as urea-formalin resin, styrene / methacrylic acid copolymer, and polystyrene resin can be used.

The leuco dyes used in the present invention are applied alone or as a mixture of two or more types. Such leuco dyes are applied to this type of recording material, and those having a lactone ring are optional. Applied to, for example, triphenylmethanephthalide, fluoran, thiofluoran, indophthalyl, spiropyran,
Leuco compounds such as azaphthalide type and bislactone type are preferably used. Examples of such compounds include, for example, those shown below.

3,3-bis (p-dimethylaminophenyl)-
Phthalide, 3,3-bis (p-dimethylaminophenyl) -6
-Dimethylaminophthalide (also known as crystal violet lactone), 3,3-bis (p-dimethylaminophenyl)
-6-diethylaminophthalide, 3,3-bis (p-dimethylaminophenyl) -6-chlorophthalide, 3,3-bis (p-
Dibutylaminophenyl) phthalide, 3-cyclohexylamino-6-chlorofluoran, 3-dimethylamino-5,
7-dimethylfluoran, 3-N-methyl-N-isobutyl-6-
Methyl-7-anilinofluoran, 3-N-ethyl-N-isoamyl-6-methyl-7-anilinofluoran, 3-diethylamino-7-chlorofluoran, 3-diethylamino-7-methylfluoran, 3-diethylamino-7,8-benzfluoran, 3-diethylamino-6-methyl-7-chlorofluoran, 3- (N-p-tolyl-N-ethylamino) -6-
Methyl-7-anilinofluoran, 3-pyrrolidino-6-
Methyl-7-anilinofluoran, 2- {N- (3'-trifluoromethylphenyl) amino} -6-diethylaminofluoran, 2- {3,6-bis (diethylamino) -9- (o-
(Chloranilino) xanthylbenzoate lactam｝, 3-diethylamino-6-methyl-7- (m-trichloromethylanilino) fluoran, 3-diethylamino-7- (o-chloroanilino) fluoran, 3-dibutylamino-7- (o -Chloroanilino) fluoran, 3-N-methyl-N-amylamino-6-methyl-7-anilinofluoran, 3-N-methyl-N
-Cyclohexylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7- (2 ', 4'-dimethylanilino ) Fluoran, 3- (N, N-diethylamino) -5
-Methyl-7- (N, N-dibenzylamino) fluoran, benzoylleucomethylene blue, 6'-chloro-8'-methoxy-benzoindolino-spiropyran, 6'-bromo-
3'-methoxy-benzoindolino-spiropyran, 3-
(2′-hydroxy-4′-dimethylaminophenyl) -3-
(2′-methoxy-5′-chlorophenyl) phthalide, 3- (2 ′
-Hydroxy-4'-dimethylaminophenyl) -3- (2 '
-Methoxy-5'-nitrophenyl) phthalide, 3- (2'-
(Hydroxy-4'-diethylaminophenyl) -3- (2'-
Methoxy-5'-methylphenyl) phthalide, 3- (2'-methoxy-4'-dimethylaminophenyl) -3- (2'-hydroxy-4'-chloro-5'-methylphenyl) phthalide, 3
-Morpholino-7- (N-propyl-trifluoromethylanilino) fluoran, 3-pyrrolidino-7-trifluoromethylanilinofluoran, 3-diethylamino-5-chloro-7- (N-benzyl-trifluoromethyl (Anilino) fluoran, 3-pyrrolidino-7- (di-p-chlorophenyl)
Methylaminofluoran, 3-diethylamino-5-chloro-
7- (α-phenylethylamino) fluoran, 3- (N-ethyl
-p-Toluidino) -7- (α-phenylethylamino) fluoran, 3-diethylamino-7- (o-methoxycarbonylphenylamino) fluoran, 3-diethylamino-5-methyl-7-
(α-phenylethylamino) fluoran, 3-diethylamino-7-piperidinofluoran, 2-chloro-3- (N-methyltoluidino) -7- (pn-butylanilino) fluoran, 3-
(N-methyl-N-isopropylamino) -6-methyl-7-anilinofluoran, 3-dibutylamino-6-methyl-7-anilinofluoran, 3,6-bis (dimethylamino) fluorenespiro ( 9,3 ′)-6′-dimethylaminophthalide, 3- (N-benzyl-N-cyclohexylamino) -5,6-benzo-7-α
-Naphthylamino-4'-bromofluoran, 3-diethylamino-6-chloro-7-anilinofluoran, 3-N-ethyl-N
-(2-ethoxypropyl) amino-6-methyl-7-anilinofluoran, 3-N-ethyl-N-tetrahydrofurfurylamino-6-methyl-7-anilinofluoran, 3-diethylamino
-6-methyl-7-mesitidino-4 ', 5'-benzofluoran, 3-
(p-dimethylaminophenyl) -3- {1,1-bis (p-dimethylaminophenyl) ethylene-2-yl} phthalide, 3- (p-dimethylaminophenyl) -3- {1,1-bis ( p-dimethylaminophenyl) ethylene-2-yl} -6-dimethylaminophthalide,
3- (p-dimethylaminophenyl) -3- (1-p-dimethylaminophenyl-1-phenylethylene-2-yl) phthalide, 3- (p-
Dimethylaminophenyl) -3- (1-p-dimethylaminophenyl-1-p-chlorophenylethylene-2-yl) -6-dimethylaminophthalide, 3- (4'-dimethylamino-2'-methoxy)-
3- (1 ''-p-dimethylaminophenyl-1 ''-p-chlorophenyl-1 '', 3 ''-butadiene-4 ''-yl) benzophthalide, 3-
(4'-Dimethylamino-2'-benzyloxy) -3- (1 ''-p-dimethylaminophenyl-1 ''-phenyl-1 '', 3 ''-butadiene-4 ''-yl) benzophthalide , 3-dimethylamino-6-dimethylamino-fluorene-9-spiro 3 ′ (6′-dimethylamino) phthalide, 3,3-bis {2- (p-dimethylaminophenyl) -2- (p-methoxyphenyl) ) Ethenyl} -4,5,6,7-tetrachlorophthalide, 3-bis {1,1-bis (4-pyrrolidinophenyl) ethylene-2-yl} -5,6-dichloro-4,7- Dibromophthalide, 3- (N, N-diethylamino) -6-methyl-7-anilino-3 ′, 4 ′, 5 ′, 6′-tetrachlorofluoran, 3- (N, N
-Diethylamino) -6-methyl-7-anilino-3 ', 6'-
Dichlorofluoran, 3- (N, N-diethylamino) -6-
Methyl-7-anilino-3 ', 4', 5 ', 6'-tetrabromofluoran, 3- (N, N-diethylamino) -6-methyl-7-anilino-3', 6'-dibromofur Oran, 3- (N, N-dinorbutylamino) -6-methyl-7-anilino-3 ′, 4 ′,
5 ', 6'-tetrachlorofluoran, 3- (N, N-dinorbutylamino) -6-methyl-7-anilino-3', 6'-dichlorofluoran, 3- (N, N-difluoro Normal butylamino)-
6-methyl-7-anilino-3 ′, 4 ′, 5 ′, 6′-tetrabromofluoran, 3- (N, N-dinorbutylamino) -6-
Methyl-7-anilino-3 ′, 6′-dibromofluoran, 3
-(N, N-dinorpentylamino) -6-methyl-7-
Anilino-3 ', 4', 5 ', 6'-tetrachlorofluoran, 3-
(N, N-dinorpentylamino) -6-methyl-7-anilino-3 ′, 6′-dichlorofluoran, 3- (N, N-dinorpentylamino) -6-methyl-7-anilino- 3 ',
4 ', 5', 6'-tetrabromofluoran, 3- (N, N-dinorpentylamino) -6-methyl-7-anilino-3 ', 6'
-Dibromofluoran, 3- (N-ethyl-N-isopentylamino) -6-methyl-7-anilino-3 ', 4', 5 ', 6'-tetrachlorofluoran, 3- (N- Ethyl-N-isopentylamino) -6-methyl-7-anilino-3 ′, 6′-dichlorofluoran, 3- (N-ethyl-N-isopentylamino)
-6-methyl-7-anilino-3 ', 4', 5 ', 6'-tetrabromofluoran, 3- (N-ethyl-N-isopentylamino) -6-methyl-7-anilino-3' , 6′-Dibromofluoran, 3- (N-n-propyl-N-isopropylamino) -6-methyl-7-anilino-3 ′, 4 ′, 5 ′, 6′-tetrachlorofluoran, 3- (N-Normalpropyl-N-isopropylamino) -6-methyl-7-anilino-3 ′, 6′-dichlorofluoran, 3- (N-normalpropyl-N-isopropylamino) -6-methyl-7- Anilino-3 ', 4', 5 ', 6'
-Tetrabromofluoran, 3- (N-normalpropyl-N-isopropylamino) -6-methyl-7-anilino-
3 ', 6'-dibromofluoran, 3- (N-normalhexyl-N-isopropylamino) -6-methyl-7-anilino-
3 ', 4', 5 ', 6'-tetrachlorofluoran, 3- (N-normalhexyl-N-isopropylamino) -6-methyl-7-
Anilino-3 ', 6'-dichlorofluoran, 3- (N-normalhexyl-N-isopropylamino) -6-methyl-7-
Anilino-3 ', 4', 5 ', 6'-tetrabromofluoran, 3-
(N-Normalhexyl-N-isopropylamino) -6-
Methyl-7-anilino-3 ′, 6′-dibromofluoran, 3
-(N-methyl-N-normalpropylamino) -6-methyl-7-anilino-3 ', 4', 5 ', 6'-tetrachlorofluoran, 3- (N-methyl-N-normalpropylamino ) −6−
Methyl-7-anilino-3 ′, 6′-dichlorofluoran, 3
-(N-methyl-N-normalpropylamino) -6-methyl-7-anilino-3 ′, 4 ′, 5 ′, 6′-tetrabromofluoran, 3- (N-methyl-N-normalpropylamino ) −6−
Methyl-7-anilino-3 ′, 6′-dibromofluoran, 3
-(N-ethyl-N-isobutylamino) -6-methyl-7-
Anilino-3 ', 4', 5 ', 6'-tetrachlorofluoran, 3-
(N-ethyl-N-isobutylamino) -6-methyl-7-anilino-3 ′, 6′-dichlorofluoran, 3- (N-ethyl-
(N-isobutylamino) -6-methyl-7-anilino-3 ′,
4 ', 5', 6'-tetrabromofluoran, 3- (N-ethyl-N
-Isobutylamino) -6-methyl-7-anilino-3 ', 6'
-Dibromofluoran, 3- (N-methyl-N-cyclohexylamino) -6-methyl-7-anilino-3 ', 4', 5 ', 6'-
Tetrachlorofluoran, 3- (N-methyl-N-cyclohexylamino) -6-methyl-7-anilino-3 ′, 6′-dichlorofluoran, 3- (N-methyl-N-cyclohexylamino) -6 -Methyl-7-anilino-3 ', 4', 5 ', 6'-tetrabromofluoran, 3- (N-methyl-N-cyclohexylamino) -6-methyl-7-anilino-3', 6 ' -Dibromofluoran, 3- (N-ethyl-N-4-oxohexylamino) -6-methyl-7-anilino-3 ', 4', 5 ', 6'-tetrachlorofluoran, 3- ( N-ethyl-N-4-oxohexylamino) -6-methyl-7-anilino-3 ′, 6′-dichlorofluoran, 3- (N-ethyl-N-4-oxohexylamino) -6-methyl -7-anilino-3 ', 4', 5 ', 6'-tetrabromofluoran, 3- (N-ethyl-N-4-oxohexylamino) -6-methyl-7-anilino-3', 6 '-Dibromo full Oran, 3- (N-isopentyl-N-3-oxopentylamino) -6-methyl-7-anilino-3 ′, 4 ′, 5 ′, 6 ′
-Tetrachlorofluoran, 3- (N-isopentyl-N-
3-oxopentylamino) -6-methyl-7-anilino-
3 ', 6'-dichlorofluoran, 3- (N-isopentyl-N
-3-oxopentylamino) -6-methyl-7-anilino-3 ', 4', 5 ', 6'-tetrabromofluoran, 3- (N-isopentyl-N-3-oxopentylamino) -6 -Methyl-
7-anilino-3 ', 6'-dibromofluoran, 3-piperidino-6-methyl-7-anilino-3', 4 ', 5', 6'-tetrachlorofluoran, 3-piperidino-6- Methyl-7-anilino-3 ', 6'-dichlorofluoran, 3-piperidino-
6-methyl-7-anilino-3 ′, 4 ′, 5 ′, 6′-tetrabromofluoran, 3-piperidino-6-methyl-7-anilino-3 ′, 6′-dibromofluoran, 3- (N-ethyl-N-furfurylamino) -6-methyl-7-anilino-3 ′, 4 ′, 5 ′,
6'-tetrachlorofluorane, 3- (N-ethyl-N-furfurylamino) -6-methyl-7-anilino-3 ', 6'-dichlorofluorane, 3- (N-ethyl-N-fluor Furylamino) -6-methyl-7-anilino-3 ', 4', 5 ', 6'-tetrabromofluoran, 3- (N-ethyl-N-furfurylamino) -6-methyl-7-anilino −3 ′, 6′-dibromofluoran and the like.

Examples of the color developer used in the thermosensitive coloring layer of the present invention include various electron-accepting compounds capable of coloring the leuco dye upon contact, such as phenolic compounds, thiophenolic compounds, thiourea derivatives, and organic compounds. Acids and metal salts thereof are preferably applied, and specific examples thereof include the following.

4,4'-isopropylidenebisphenol,
4,4′-isopropylidenebis (o-methylphenol),
4,4'-secondary butylidenebisphenol 4,4'-isopropylidenebis (2-tert-butylphenol), 4,4'-cyclohexylidenediphenol, 4,4'-
Isopropylidenebis (2-chlorophenol), 2,2'-
Methylenebis (4-methyl-6-tert-butylphenol), 2,2′-methylenebis (4-ethyl-6-tert-butylphenol), 4,4′-butylidenebis (6-tert-butyl-2-methylphenol), 1 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,1,3-tris (2-methyl-4-hydroxy-
5-cyclohexylphenyl) butane, 4,4'-thiobis (6
-Tert-butyl-2-methylphenol), 4,4'-
Diphenolsulfone, 4-isopropoxy-4'-hydroxydiphenylsulfone, 4-benzyloxy-4'-hydroxydiphenylsulfone, 4,4'-diphenolsulfoxide, isopropyl P-hydroxybenzoate, benzyl P-hydroxybenzoate Benzyl protocatechuate, stearyl gallate, lauryl gallate, octyl gallate, 1,7-bis (4-hydroxyphenylthio) -3,5-dioxaheptane, 1,5-bis (4-hydroxyphenylthio) -3-oxapentane, 1,3-bis (4-hydroxyphenylthio) -propane, 1,3-bis (4-hydroxyphenylthio) -2-hydroxypropane, N, N'-diphenylthiourea, N, N'-di (m-chlorophenyl) thiourea, salicylanilide, 5-chloro-salicylanilide, 2-hydroxy-3-naphthoic acid, 2-hydroxy-1- Futoe acid, 1-hydroxy-2-naphthoic acid, zinc hydroxynaphthoic acid, aluminum, metal salts such as calcium,
Bis- (4-hydroxyphenyl) acetic acid methyl ester, bis- (4-hydroxyphenyl) acetic acid benzyl ester, 1,3
-Bis (4-hydroxycumyl) benzene, 1,4-bis (4-
(Hydroxycumyl) benzene, 2,4′-diphenolsulfone, 3,3′-diallyl-4,4′-diphenolsulfone,
α, α-bis (4-hydroxyphenyl) -α-methyltoluene, antipyrine complex of zinc thiocyanate, tetrabromobisphenol A, tetrabromobisphenol S, 4,
4'-thiobis (2-methylphenol), 4,4'-thiobis (2-methylphenol)
Chlorophenol) and the like.

In order to produce the heat-sensitive recording material of the present invention,
When the leuco dye and the developer are bound and supported on the support, various conventional binders can be appropriately used, and specific examples thereof include the following.

Cellulose derivatives such as polyvinyl alcohol, starch and derivatives thereof, hydroxymethylcellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose and ethylcellulose, and polyacrylic acid -Da, polyvinylpyrrolidone, acrylamide / acrylate copolymer, acrylamide / acrylate / methacrylic acid terpolymer, styrene /
Maleic anhydride copolymer alkali salt, isobutylene / maleic anhydride copolymer alkali salt, polyacrylamide, sodium alginate, gelatin, casein and other water-soluble polymers, polyvinyl acetate, polyurethane, polyacrylic acid, Polyacrylate, vinyl chloride / vinyl acetate copolymer, polybutyl methacrylate, ethylene /
Emulsions such as vinyl acetate copolymers and latexes such as styrene / butadiene copolymers and styrene / butadiene / acrylic copolymers.

In the present invention, various heat-fusible substances can be used as the sensitivity improver, and specific examples thereof include the following, but are not limited thereto. . Fatty acids such as stearic acid and behenic acid, fatty acid amides such as stearic acid amide and palmitic acid amide, fatty acid metal salts such as zinc stearate, aluminum stearate, calcium stearate, zinc palmitate and zinc behenate, p-benzyl Biphenyl, terphenyl, triphenylmethane, benzyl p-benzyloxybenzoate, β-benzyloxynaphthalene, phenyl β-naphthoate, phenyl 1-hydroxy-2-naphthoate, methyl 1-hydroxy-2-naphthoate, diphenyl Carbonate, gliacol carbonate, dibensil terephthalate, dimethyl terephthalate, 1,4-dimethoxynaphthalene, 1,4-diethoxynaphthalene, 1,4-dibenzyloxynaphthalene, 1,2-diphenoxyethane, 1,2 -
Bis (3-methylphenoxy) ethane, 1,2-bis (4-methylphenoxy) ethane, 1,4-diphenoxy-2-butene, 1,2-
Bis (4-methoxyphenylthio) ethane, dibenzoylmethane, 1,4-diphenylthiobutane, 1,4-diphenylthio
2-butene, 1,3-bis (2-vinyloxyethoxy) benzene, 1,4-bis (2-vinyloxyethoxy) benzene, p- (2
-Vinyloxyethoxy) bifer, p-aryloxyphenyl, p-propargyloxybiphenyl, dibenzoyloxymethane, dibenzoyloxypropane, dibenzyldisulfide, 1,1-diphenylethanol, 1,1-diphenylpropanol, p -Benzyloxybenzyl alcohol, 1,3-phenoxy-2-propanol, N-octadecylcarbamoyl-p-methoxycarbonylbenzene, N-
Octadecylcarbamoylbenzene, 1,2-bis (4-methoxyphenoxy) propane, 1,5-bis (4-methoxyphenoxy) -3-oxapentane, dibenzyl oxalate, bis (4-methylbenzyl) oxalate, oxalic acid Bis (4-chlorobenzyl) and the like.

When a thermosensitive recording material is to be obtained according to the present invention, if necessary, together with a leuco dye, a developer and the compound of the present invention, additional components commonly used in this type of thermosensitive recording material, such as fillers and surfactants Agents and the like can be used in combination. In this case, as a filler, for example, calcium carbonate, silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide,
Inorganic fine powders such as barium sulfate, clay, kaolin, talc, surface-treated calcium and silica, and urea
Examples include organic fine powders such as formalin resin, styrene-methacrylic acid copolymer, polystyrene resin, and vinylidene chloride resin. Further, regarding the layer structure, a single layer or a multilayer may be used, and if necessary, an over layer,
An under layer and a back layer can be provided.

In the present invention, a layer containing a pigment, a binder, a heat-fusible substance and the like can be provided between the intermediate layer and the heat-sensitive coloring layer, if necessary, as another intermediate layer.

Further, in the recording material of the present invention, it is possible to provide a protective layer on the heat-sensitive recording layer for the purpose of improving the storage stability of the recorded image or improving the writability of the recording material. In this case, as the components constituting the protective layer, the above-mentioned pigments, binders, heat-fusible substances and the like can be used.

[0037]

Next, the present invention will be described in more detail with reference to examples. All parts and percentages shown below are based on weight.

Example 1 (Reference Example) and Comparative Examples 1-1 to 1-3 Uncured microcapsules containing a color developing compound were formed according to the microencapsulation method (coacervation method) shown below. Was cured to obtain microcapsules of a color developable compound having a particle size of 1 to 3 μm. [Microencapsulation method] One part of a color developing compound is dissolved in 5 parts of acetone to prepare a color developer solution, which is used as a core substance. (I) Production of Uncured Encapsulated Product A color developing compound solution as a core substance is emulsified and dispersed in a 40 ° C. gelatin aqueous solution containing sodium dodecyl sulfate as a surfactant using an ultrasonic emulsifier. The particle size of the color-developing compound solution is measured by a light scattering method and emulsified and dispersed so as to always have a constant particle size. Next, this emulsified product was
Disperse in an aqueous solution of gum arabic at 0 ° C. to make the whole 1 liter.
Coacervation occurs when the pH of the system is lowered to the isoelectric point of gelatin with a 2.5% acetic acid aqueous solution with stirring,
A coacervate phase composed of gelatin and gum arabic precipitates around the color developing compound solution to form a film, and uncured microcapsules are formed. (Ii) Curing of Uncured Encapsulated Material After setting the uncured microcapsules produced above at 20 ° C. below the set point of the gelatin, 1 ml of 37% formalin aqueous solution is added to the system, and then the pH of the system is adjusted. To 2.
Raising the pH to 8.5 with a 5% aqueous sodium carbonate solution hardens the gelatin and makes it insoluble in water. After the capsule dispersion liquid is centrifuged, the obtained capsule slurry is dried by spray drying to obtain a hardened encapsulated product in which the target color developing compound solution is encapsulated.

Next, the following mixture 9 was mixed well with [A-1] using a stirrer, and [B] and [C] were each pulverized in a magnetic ball mill for 2 days to prepare. [A-1 solution] Microcapsules of the color-developing compounds shown in Table 4 30 parts 10% aqueous solution of polyvinyl alcohol 20 parts Water 50 parts [Solution B] 3- (N-methyl-N-cyclohexyl) amino-6-methyl -7-anilinofluorane 20 parts 10% aqueous solution of polyvinyl alcohol 20 parts Water 60 parts [Solution C] calcium carbonate 20 parts 5% aqueous solution of methylcellulose 20 parts Water 60 parts

Next, 10 parts of [A-1 solution] and 30 parts of [B solution]
, 30 parts of [solution C] and 10 parts of a 20% aqueous alkali solution of isobutylene / maleic anhydride copolymer to obtain a thermosensitive coloring layer-forming solution, which was dried on a high quality paper having a basis weight of 50 g / m ² . After coating and drying to provide a thermosensitive coloring layer so that the amount of dye attached becomes 0.5 g / m ² , the surface smoothness is further increased to 50 g / m ^2.
The layer surface was calendered so as to be 0 to 600 seconds to prepare a heat-sensitive recording material.

The heat-sensitive recording material thus prepared was brought into contact with a hot plate at 150 ° C. for 5 seconds at a pressure of 1 kg / cm ² for 5 seconds by a thermal gradient tester to obtain a color image, and the color density was measured by a Macbeth densitometer. The concentration was measured by RD-914, and this was used as data before the test. Next, the following test was performed on this sample, and the image density was used as data after the test. [Test I] Cotton seed oil was applied to the sample before the test, and the temperature was 4
Leave at 0 ° C. for 100 hours. [Test II] A sample before the test was subjected to a temperature of 40 ° C and a humidity of 90%.
For 48 hours in the environment described above. Table 4 shows the results.

[0042]

[Table 4]

Examples 2-1 to 2-3 and Comparative Examples 2-1 to 2-5 Each of the following mixtures was pulverized for 2 days in a magnetic ball mill, [liquid A-2], [liquid B] and [liquid B]. Solution C] was prepared. [A-2 solution] Developing compound in Table 5 20 parts 10% aqueous solution of polyvinyl alcohol 20 parts Water 60 parts [Solution B] 3- (N-methyl-N-cyclohexyl) amino-6-methyl-7- Anilinofluorane 20 parts 10% aqueous solution of polyvinyl alcohol 20 parts Water 60 parts [Solution C] Calcium carbonate 20 parts 5% aqueous solution of methylcellulose 20 parts Water 60 parts

Next, 30 parts of [solution A-2] and 10 parts of [solution B]
, 30 parts of [solution C] and 10 parts of a 20% aqueous alkali solution of isobutylene / maleic anhydride copolymer to obtain a thermosensitive coloring layer-forming solution, which was dried on a high quality paper having a basis weight of 50 g / m ² . After coating and drying to provide a thermosensitive coloring layer so that the amount of dye attached becomes 0.5 g / m ² , the surface smoothness is further increased to 50 g / m ^2.
The layer surface was calendered so as to be 0 to 600 seconds to prepare a heat-sensitive recording material.

The heat-sensitive recording material prepared as described above was brought into contact with a hot plate at 150 ° C. at a pressure of 1 kg / cm ² for 5 seconds by a thermal gradient tester to obtain a color image, and the color density was measured using a Macbeth densitometer. The concentration was measured by RD-914, and this was used as data before the test. Next, the following test was performed on this sample, and the image density was used as data after the test. [Test I] Cotton seed oil was applied to the sample before the test, and the temperature was 4
Leave at 0 ° C. for 100 hours. [Test II] A sample before the test was subjected to a temperature of 40 ° C and a humidity of 90%.
For 48 hours in the environment described above. Table 5 shows the results.

[0046]

[Table 5]

Examples 3-1 to 3-2 and Comparative Examples 3-1 to 3-3 The following mixture was stirred and dispersed to obtain an intermediate layer forming liquid. [Liquid D] Fine hollow particle dispersion (copolymer resin mainly composed of styrene and acrylic) (solid content: 38%, average particle diameter: 0.7 μm, hollow ratio: 80%, 30 parts styrene / butadiene copolymer latex (solid 10 parts water 60 parts The above-mentioned intermediate layer forming liquid was prepared by using a commercially available high-quality paper (basis weight: 52 g /
m ² ) was dried and then applied and dried to a weight of 5 g / m ² to obtain an intermediate layer coated paper. The following mixtures were each pulverized for 2 days in a magnetic ball mill [Solution A-3],
[Solution B] and [Solution C] were prepared. [A-3 solution] Developing compounds in Table 6 20 parts 10% aqueous solution of polyvinyl alcohol 20 parts Water 60 parts [Solution B] 3- (N-methyl-N-cyclohexyl) amino-6-methyl-7- Anilinofluorane 20 parts 10% aqueous solution of polyvinyl alcohol 20 parts Water 60 parts [Solution C] Calcium carbonate 20 parts 5% aqueous solution of methylcellulose 20 parts Water 60 parts

Next, 30 parts of [A-3 solution], 10 parts of [B solution] 10
Part, [C solution] 40 parts and Chukyo Yushi's zinc stearate dispersion (hydrin Z730, 30% concentration, 30%) were mixed to form a thermosensitive coloring layer forming liquid, which was applied to the surface of the above-mentioned intermediate layer coated paper. After coating and drying to provide a heat-sensitive coloring layer so that the dye adhesion amount after drying becomes 0.5 g / m ² , the layer surface is calendered so that the surface smoothness is 500 to 600 seconds, and then heat-sensitive. A recording material was produced.

The thermal recording material obtained as described above was applied to a thermal printing apparatus manufactured by Matsushita Parts Co., Ltd. at a voltage of 13.
Printing was performed with a 3 V pulse of φ0.7 ms to obtain a color image, and the color density was measured with a Macbeth densitometer RD-914 to obtain data before the test. Next, the following test was performed on this sample, and the image density was used as data after the test. [Test I] Cotton seed oil was applied to the sample before the test, and the temperature was 4
Leave at 0 ° C. for 16 hours. [Test II] A sample before the test was subjected to a temperature of 40 ° C and a humidity of 90%.
In the environment for 16 hours. Table 6 shows the results.

[0050]

[Table 6]

[0051]

The heat-sensitive recording material of the present invention has the general formula
By using the color-developing compound represented by (I) ,
It becomes excellent in storage stability of a color image. Further, by providing an intermediate layer mainly composed of plastic spherical hollow particles, energy efficiency from a thermal head or the like is improved, and formation of a high-density image with low energy becomes easy.

[Brief description of the drawings]

FIG. 1 is an infrared absorption spectrum of a ring-opened product obtained by reacting 3- (N, N-diethylamino) -6-methyl-7-anilinofluoran with methyl iodide.

FIG. 2 is a view of the magnetic resonance spectrum of a ring-opened product obtained by reacting 3- (N, N-diethylamino) -6-methyl-7-anilinofluoran with methyl iodide.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-146846 (JP, A) JP-A-63-170083 (JP, A) JP-A-62-35881 (JP, A) JP-A-4- 153080 (JP, A) JP-A-6-55847 (JP, A) JP-A-6-122279 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41M 5/30

Claims (2)

(57) [Claims] 1. A leuco dye having a lactone ring on a support and developing a color by opening the lactone ring, and the following general formula ( I) acting on an irreversible ring-opening reaction of the lactone ring of the leuco dye. A heat-sensitive recording material comprising a heat-sensitive coloring layer containing a color-developing compound represented by the formula (1) as a main component. Embedded image (Wherein, R ₁ represents an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group, and R _{2 to} R ₆ represent a hydrogen, a halogen, a hydroxyl group, a nitro group, an amino group, an alkyl group, an alkenyl group, an aralkyl group, an aryl group. A group and a group in which these groups are linked by a carbonyl group, or these groups may form a ring with each other. Y represents an anion having a —SO ₃ group.) Wherein between the support and on the thermosensitive coloring layer, the heat-sensitive recording material according to claim 1 Symbol mounting, characterized in that an intermediate layer mainly composed of plastic spherical hollow particles.